The mechanism of memory
Bacopa monniera and Centella asiatica
Comparative modes of action of the major cognition-facilitating nutraceuticals
Traditional uses of Bacopa : contemporary relevance
Other pharmacological effects of Bacopa monniera

The hippocampus, the brain's seat of memory, is located in the temporal (left and right) sides of the brain. It processes signals sent to the brain by the senses into the templates of memory, which are then stored in other parts of the brain, creating a long-term memory. Signals are converted into electrical impulses in the nerve cells due to a rapid change in protein composition. These impulses are then conducted across neurons (nerve cells) and through synapses, which connect nerve cells. This process continues until the bonds between the nerve cells strengthen, and memory is created.

Normal synaptic activity is a process mediated by neurotransmitters. Each neuron is a single nerve cell. It has one or more arms called axons that send signals (impulses) and one or more arms called dendrites that receive signals. When a signal is transmitted through an axon terminal, spherical bodies called vesicles fuse with its membrane. Neurotransmitters are released when the vesicles burst open into the synaptic space, the minute space between the sending and receiving cells used to discharge neurotransmitters ("passengers"). To end the signal, the axons reabsorb some neurotransmitters; and the enzymes in the synapse neutralize the other neurotransmitters. (Fig. 1.2)



Figure 1.2 Schematic representation of the mechanism of synaptic activity

It is evident that a disruption in any part of normal synaptic activity would affect memory. This normally occurs with advanced age and continuous electrical activity, which wears out the synapses. As a result, new memory creation is impaired and memory loss occurs.

Chemical substances and plant extracts that are known to restore the memory work in different ways. The bacosides are the memory chemicals in Brahmi. According to scientists at the Central Drug Research Institute located in Lucknow, India, the bacosides help to repair damaged neurons by adding muscle to kinase, the protein involved in the synthesis of new neurons to replace the old ones. Depleted synaptic activity is thus restored, leading to augmented memory functions. The possible mode of action of Brahmi is schematically represented in Fig. 1.3.



A pyramidal cell from the hippocampus :
the sites of memory are located on the "branches"



Figure 1.3 Postulated mode of action of Brahmi in boosting memory functions

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